1. Technical Field
The technical field relates to a liquid crystal display (LCD) device, and more particularly, to a driving apparatus and method of an LCD device to improve brightness and contrast ratio of image.
2. Discussion of the Related Art
An LCD device displays images by controlling light transmittance of liquid crystal cells according to video signals. The LCD device may be formed in an active matrix type which may include switching devices in the liquid crystal cells. The LCD device may be used for monitors of a computer, office equipment, a cellular phone, and other electronic devices. The switching devices used for the LCD device of the active matrix type may be formed of thin film transistors (hereinafter, referred to as “TFTs”).
FIG. 1 is a block diagram of a driving apparatus of an LCD device according to the related art. Referring to FIG. 1, the driving apparatus of the LCD device according to the related art may include an LCD panel 2, a data driver 4, a gate driver 6, a gamma voltage supplier 8, a timing controller 10, a DC/DC converter 14, and an inverter 16.
In the LCD panel 2, ‘m×n’ liquid crystal cells (where m and n are natural numbers) (Clc) are arranged in a matrix type, and a plurality of TFTs may be formed adjacent to crossings of gate and data lines. Also, the data driver 4 supplies a data signal to the data lines (DL1 to DLm), and the gate driver 6 supplies a scan signal to the gate lines (GL1 to GLn). Also, the gamma voltage supplier 8 supplies a gamma voltage to the data driver 4. The timing controller 10 controls the data driver 4 and the gate driver 6 with synchronization signals provided from a system 20. Also, the DC/DC converter 14 generates voltages for the LCD panel 2 with voltages provided from a power supplier 12. The inverter 16 drives a backlight 18.
The system 20 supplies horizontally and vertically synchronized signals (Hsync and Vsync), a clock signal (DCLK), a data enable signal (DE), and data (R, G, B signal components) to the timing controller 10. The LCD panel 2 may include the plurality of liquid crystal cells (Clc) arranged in the matrix type and formed adjacent to the crossings of the gate lines (GL1 to GLn) and the data lines (DL1 to DLm). The plurality of TFTs formed in the respective liquid crystal cells (Clc) respond to the scan signal provided from the gate lines (GL), and supply the data signal provided from the data lines (DL) to the liquid crystal cells (Clc). Also, a storage capacitor (Cst) may be formed in each of the liquid crystal cells (Clc). The storage capacitor (Cst) may be formed between the preceding gate line and a pixel electrode of the liquid crystal cell (Clc), or may be formed between a common electrode line and the pixel electrode of the liquid crystal cell (Clc), to maintain a constant voltage in the liquid crystal cell (Clc).
The gamma voltage supplier 8 supplies a plurality of the gamma voltages to the data driver 4. The data driver 4 responds to a control signal (CS) provided from the timing controller 10, converts data (R,G, B signal components) to an analog gamma voltage (data signal) corresponding to a gray scale value, and supplies the analog gamma voltage to the data lines (DL1 to DLm). Also, the gate driver 6 responds to the control signal (CS) provided from the timing controller 10, sequentially supplies the scan signal to the gate lines (GL1 to GLn), and selects a horizontal line of the LCD panel 2 to which the data signal is supplied.
The timing controller 10 generates the control signals (CS) for controlling the gate driver 6 and the data driver 4 using the horizontally and vertically synchronized signals (Hsync and Vsync), and the clock signal (DCLK). At this time, the control signal (CS) for controlling the gate driver 6 may include a gate start-pulse (GSP), a gate shift clock (GSC), and a gate output enable (GOE). Also, the control signal (CS) for controlling the data driver 4 may include a source start pulse (SSP), a source shift clock (SSC), a source output enable (SOE), and a polarity signal (POL). The timing controller 10 re-arranges the data (R, G, B) provided from the system 20, and then supplies the re-arranged data (R, G, B) to the data driver 4.
The DC/DC converter 14 generates the voltage provided to the LCD panel 2 by increasing or decreasing a 3.3V provided from the power supplier 12. The DC/DC converter 14 generates a gamma reference voltage, a gate high voltage (VGH), a gate low voltage (VGL), and a common voltage (Vcom). Also, the inverter 16 supplies a lamp driving voltage for driving the backlight 18 to the LCD panel 2. The backlight 18 generates the light corresponding to the lamp driving voltage supplied from the inverter 16, and supplies the generated light to the LCD panel 2.
To obtain vivid images by improving picture quality of the images displayed in the above LCD panel 2, it is necessary to improve the contrast ratio between dark and bright images. In the case of the related art LCD device, there is no way to improve the contrast ratio in accordance with the data. Also, the backlight 18 of the related art LCD device emits light of a constant level regardless of the data, so that it is difficult to obtain the vivid images. For example, when displaying the scene of explosion, there is requirement for emphasizing the brightness in the exploding portion. However, the related art LCD device may include a backlight 18 emitting light of a constant level, whereby the related art LCD device has no vivid images. Therefore, a need exists for improvements to contrast level displays in LCD devices.